When talking to customers, pay more attention in the answers they want to give than in the answer you wanted to get. The parent assumed it was by month and not

When talking to customers, pay more attention in the answers they want to give than in the answer you wanted to get. The parent assumed it was by month and not mentioned it being too high. So, clear indication that $15/year do not present itself as too high without any further info. And as other commented, it might be too low. As I type this, both primary comments have very valuable advice. Listen to them and not to the fact they did not answered your proposed question.